The humdity will rise as the chicks hatch. I have been told by someone who hatches frequently that she tries to keep it from going over 75% or so but, that she doesn't believe that at this stage it would really hurt anything if it went higher.

I vent more for a sec to bring it down, just what I do cuz I have lost some that seemed to drown and since I dry incubate, I know it wasn't from that. I usually just pull the empty shells, that seems to help. JMO